An analysis of the Justice Department's own list of terrorism prosecutions by The Washington Post shows that 39 people — not 200, as officials have implied — were convicted of crimes related to terrorism or national security.

Most of the others were convicted of relatively minor crimes such as making false statements and violating immigration law — and had nothing to do with terrorism, the analysis shows. For the entire list, the median sentence was just 11 months.

Taken as a whole, the data indicate that the government's effort to identify terrorists in the United States has been less successful than authorities have often suggested. The statistics provide little support for the contention that authorities have discovered and prosecuted hundreds of terrorists here. Except for a small number of well-known cases — such as truck driver Iyman Faris, who sought to take down the Brooklyn Bridge — few of those arrested appear to have been involved in active plots inside the United States.

Among all the people charged as a result of terrorism probes in the three years after the Sept. 11, 2001, attacks, The Post found no demonstrated connection to terrorism or terrorist groups for 180 of them.

Just one in nine individuals on the list had an alleged connection to the al Qaeda terrorist network and only 14 people convicted of terrorism-related crimes — including Faris and convicted Sept. 11 plotter Zacarias Moussaoui — have clear links to the group. Many more cases involve Colombian drug cartels, supporters of the Palestinian cause, Rwandan war criminals or others with no apparent ties to al Qaeda or its leader, Osama bin Laden.

Chance arrestsBut a large number of people appear to have been swept into U.S. counterterrorism investigations by chance — through anonymous tips, suspicious circumstances or bad luck — and have remained classified as terrorism defendants years after being cleared of connections to extremist groups.

For example, the prosecution of 20 men, most of them Iraqis, in a Pennsylvania truck-licensing scam accounts for about 10 percent of individuals convicted — even though the entire group was publicly absolved of ties to terrorism in 2001.